Difference between revisions of "2000 AMC 10 Problems/Problem 11"
(New page: Two prime numbers between <math>4</math> and <math>18</math> are both odd. odd*odd=odd. odd-odd-odd=odd. Thus, we can discard the even choices. <math>ab-a-b=(a-1)(b-1)-1</math>. <mat...) |
(No difference)
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Revision as of 15:06, 7 January 2009
Two prime numbers between 
and 
are both odd.
odd*odd=odd.
odd-odd-odd=odd.
Thus, we can discard the even choices.
.
.
Both of these factors are even, so the number +1 must be a multiple of .
is the only possiblity.
satisfy this, 
.
C.
